U.S. patent application number 12/289784 was filed with the patent office on 2009-05-14 for rolling bearing.
This patent application is currently assigned to JTEKT Corporation. Invention is credited to Katsunori Otsuka.
Application Number | 20090123100 12/289784 |
Document ID | / |
Family ID | 40398199 |
Filed Date | 2009-05-14 |
United States Patent
Application |
20090123100 |
Kind Code |
A1 |
Otsuka; Katsunori |
May 14, 2009 |
Rolling bearing
Abstract
Surfaces of the raceway grooves of the outer and inner rings, a
surface of each ball and all surface of the cage are coated with
titanium oxide. In other words, hydrophilic layers made of titanium
oxide are formed on the surfaces of the raceway grooves of the
outer and inner rings, the surface of each ball and all surface of
the cage.
Inventors: |
Otsuka; Katsunori; (Osaka,
JP) |
Correspondence
Address: |
MCGINN INTELLECTUAL PROPERTY LAW GROUP, PLLC
8321 OLD COURTHOUSE ROAD, SUITE 200
VIENNA
VA
22182-3817
US
|
Assignee: |
JTEKT Corporation
Osaka
JP
|
Family ID: |
40398199 |
Appl. No.: |
12/289784 |
Filed: |
November 4, 2008 |
Current U.S.
Class: |
384/463 ;
384/569 |
Current CPC
Class: |
F16C 33/445 20130101;
F16C 19/06 20130101; F16C 33/62 20130101; F16C 33/32 20130101; F16C
33/6692 20130101; F16C 33/44 20130101; F16C 33/6696 20130101; F16C
2210/10 20130101 |
Class at
Publication: |
384/463 ;
384/569 |
International
Class: |
F16C 19/00 20060101
F16C019/00; F16C 33/58 20060101 F16C033/58 |
Foreign Application Data
Date |
Code |
Application Number |
Nov 14, 2007 |
JP |
P2007-295631 |
Claims
1. A rolling bearing comprising: a bearing ring; a rolling element;
and a cage, wherein at least one of a raceway surface of the
bearing ring, a rolling contact surface of the rolling element and
a guide face of a pocket of the cage for guiding the rolling
element has a hydrophilic layer made of a material having a
hydrophilic property, and lubrication is made with water retained
by the hydrophilic layer.
2. The rolling bearing according to claim 1, wherein the raceway
surface of the bearing ring or the rolling contact surface of the
rolling element includes a portion not having the hydrophilic layer
and said portion includes a solid lubrication layer made of a solid
lubricant.
3. The rolling bearing according to claim 1, wherein the cage is
made of a material added with solid lubricant or made of
fluororesin having a lubrication property.
4. The rolling bearing according to claim 1, wherein at least one
of the raceway surface of the bearing ring, the rolling contact
surface of the rolling element and the guide face of the pocket of
the cage is coated with titanium oxide.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a rolling bearing. More
particularly, the present invention relates to a rolling bearing
used in an environment in which water, steam or chemical fluid
containing water is scattering. Especially, the present invention
relates to a rolling bearing preferably used for a liquid crystal
device or a washing device.
[0003] 2. Related Art
[0004] Conventionally, in the case where the rolling bearing is
used in an environment in which water or liquid containing water is
scattering, it is used under the condition of no lubrication or
alternatively it is used being lubricated by solid lubricant.
[0005] However, it is clear that the rolling bearing is used under
the condition of no lubrication. Even in the case where the rolling
bearing is lubricated by solid lubricant, since the solid lubricant
functions as lubricant when it is abraded. Therefore, when all the
solid lubricant has been abraded, the lubricating function is lost.
See, for example, JP-A-9-42296.
SUMMARY OF THE INVENTION
[0006] An object of the present invention is to provide a rolling
bearing capable of being positively lubricated over a long period
of time in an environment in which water, steam or chemical fluid
containing water is scattering.
[0007] In order to accomplish the above object, a rolling bearing
of the present invention comprises: a bearing ring; a rolling
element; and a cage, wherein
[0008] at least one of the raceway surface of the bearing ring, the
rolling contact surface of the rolling element and the guide face
of the pocket of the cage for guiding the rolling element has a
hydrophilic layer made of material having a hydrophilic property,
and
[0009] lubrication is made with water retained by the hydrophilic
layer.
[0010] Examples of the material having the hydrophilic property
are: titanium oxide, material containing titanium oxide,
polyoxysilyl compound and material having a hydroxyl group such as
polypropylene.
[0011] According to the present invention, at least one of the
raceway surface of the bearing ring, the rolling contact surface of
the rolling element and the guide face of the pocket of the cage
has a hydrophilic layer made of material having a hydrophilic
property. Therefore, it is possible to retain scattering water by
this hydrophilic layer. Accordingly, it is possible to lubricate
the rolling bearing by the thus retained water.
[0012] Accordingly, when this rolling bearing is used in an
environment in which water, steam or chemical fluid containing
water is scattering, the hydrophilic layer and a portion, which
comes into sliding contact with the hydrophilic layer, can be
always lubricated by water. Therefore, the hydrophilic layer and
the portion, which comes into sliding contact with the hydrophilic
layer, can be put into an excellent lubricating condition at all
times while the rolling bearing is being used.
[0013] In the case of a constitution in which titanium oxide or
material containing titanium oxide is used as hydrophilic material
and further no sealing member is provided in the rolling bearing,
that is, in an environment in which the sunlight and ultraviolet
rays can intrude into the rolling bearing, the contamination
attached to the hydrophilic layer can be dissolved into carbon
dioxide by the photocatalystic action of titanium oxide.
Accordingly, the hydrophilic layer can be washed and maintained in
a clean condition.
[0014] In one embodiment, no hydrophilic layer is provided in a
portion of the raceway surface of the bearing ring and the rolling
contact surface of the rolling element. This portion has a solid
lubricating layer made of solid lubricant.
[0015] According to the above embodiment, no hydrophilic layer is
provided in a portion of the raceway surface of the bearing ring
and the rolling contact surface of the rolling element. This
portion has a solid lubricating layer made of solid lubricant.
Therefore, until the solid lubricant is abraded away, all the
raceway surface of the bearing ring and the rolling contact surface
of the rolling element can be lubricated in a good condition.
[0016] In one embodiment, the cage is made of material added with
solid lubricant or made of fluororesin having a lubrication
property.
[0017] According to the above embodiment, by the synergistic effect
of the lubricating actions of the hydrophilic layer and the cage,
the lubricating property can be greatly enhanced beyond estimation
as compared with a rolling bearing, the cage of which is made of
material to which the solid lubricant is added, or material of
fluororesin having a lubricating property.
[0018] According to the rolling element of the present invention,
the hydrophilic layer and the portion, which comes into sliding
contact with the hydrophilic layer, can be always lubricated by
water. Therefore, the hydrophilic layer and the portion, which
comes into sliding contact with the hydrophilic layer, can be put
into an excellent lubricating condition at all times while the
rolling bearing is being used.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a schematic sectional view showing a ball bearing
of the first embodiment of the present invention.
[0020] FIG. 2 is a schematic sectional view showing a ball bearing
of the second embodiment of the present invention.
[0021] FIG. 3 is a schematic sectional view showing a ball bearing
of the third embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] An embodiment of the present invention will be explained in
detail, referring to the drawings.
[0023] FIG. 1 is a schematic sectional view in the axial direction
of a ball bearing which is the first embodiment of the rolling
bearing of the present invention.
[0024] This ball bearing pivotally supports a drive shaft of a
liquid crystal device and is installed in an environment in which
water is being scattered outside the ball bearing.
[0025] This ball bearing includes: an outer ring 1 which is a
bearing ring; an inner ring 2 which is a bearing ring; a plurality
of balls 3 which are rolling elements; a cage 4 for holding the
balls 3; a first shielding plate 6; and a second shielding plate
7.
[0026] The outer ring 1 includes: a raceway groove 11 which is
formed on an inner circumferential face of the outer ring 1 and
used as a raceway surface; a first shielding plate attaching
groove, the shape of which is annular; and a second shielding plate
attaching groove, the shape of which is annular. The raceway groove
11 is located in a central portion in the axial direction on the
inner circumferential face. The first shielding plate attaching
groove is located in one end portion in the axial direction on the
inner circumferential face. The second shielding plate attaching
groove is located in the other end portion in the axial direction
on the inner circumferential face.
[0027] The inner ring 2 includes a raceway groove 21 which is a
raceway surface and formed in a central portion on the outer
circumferential face.
[0028] The plurality of balls 3 are arranged between the raceway
groove 11 of the outer ring 1 and the raceway groove 21 of the
inner ring 2 in the circumferential direction at regular intervals
being held by the cage 4. The cage 4 is made of PEEK resin
(polyether etherketon) or PPS resin (polyphenylene sulfide). The
cage 4 includes a pocket 25 for accommodating the balls 3. The
balls 3 are guided by the ball guide face 28 of the pocket 25.
[0029] The first shielding plate 6 airtightly closes one opening in
the axial direction between the outer ring 1 and the inner ring 2.
One end portion outward in the radial direction of the first
shielding plate 6 is fixed into the first shielding plate attaching
groove. On the other hand, the other end portion inward in the
radial direction is opposed to the outer circumferential face of
the inner ring 2 while leaving a small gap in the radial direction.
The other end portion inward in the radial direction of the first
shielding plate 6 and a portion on the outer circumferential face
of the inner ring 2, which is opposed to this other end portion in
the radial direction, form a labyrinth seal.
[0030] The second shielding plate 7 airtightly closes one opening
in the axial direction between the outer ring 1 and the inner ring
2. One end portion outward in the radial direction of the second
shielding plate 7 is fixed into the second shielding plate
attaching groove. On the other hand, the other end portion inward
in the radial direction is opposed to the outer circumferential
face of the inner ring 2 while leaving a small gap in the radial
direction. The other end portion inward in the radial direction of
the second shielding plate 7 and a portion on the outer
circumferential face of the inner ring 2, which is opposed to this
other end portion in the radial direction, form a labyrinth seal.
Inside the ball bearing, water, which has passed through the
labyrinth seal, are scattering at the time of using the ball
bearing.
[0031] The raceway groove 11 of the outer ring 1, the raceway
groove 21 of the inner ring 2, the surface (the rolling contact
surface) of each ball 3 and all the surface of the cage 4 are
coated with titanium oxide which is an example of the hydrophilic
material. In other words, the surfaces of the raceway groove 11 of
the outer ring 1, the raceway groove 21 of the inner ring 1, each
ball 3 and cage 4 have hydrophilic layers (not shown) made of
titanium oxide.
[0032] According to the ball bearing of the first embodiment
described above, the raceway grooves 11, 21 of the inner and outer
rings 1, 2, the surfaces of the balls 3 (the rolling contact
surfaces) and the ball guide face 28 of the pocket 25 of the cage 4
have hydrophilic layers made of titanium oxide having a hydrophilic
property. At the time of using the ball bearing, water is
scattering in the ball bearing. Therefore, it is possible to retain
the scattering water by this hydrophilic layer. By the thus
retained water, it is possible to lubricate the raceway grooves 11,
21 of the inner and outer rings 1, 2, the surfaces of the balls 3
(the rolling contact surfaces) and the ball guide face 28 of the
pocket 25 of the cage 4. Therefore, seizure of the sliding portion
can be positively prevented over a long period of time.
[0033] In the ball bearing of the first embodiment described above,
titanium oxide is used as material having a hydrophilic property.
However, in the present invention, it is possible to use a compound
material containing titanium oxide, polyoxysilyl compound and
material having a hydroxyl group such as polypropylene as
hydrophilic material. In this rolling bearing, as long as the
material is hydrophilic, any material may be used.
[0034] According to the ball bearing of the first embodiment
described above, the raceway grooves 11, 21 of the inner and outer
rings 1, 2, the rolling contact surfaces of the balls 3 and all the
surface of the cage 4 are coated with titanium oxide which is an
example of the hydrophilic material. However, in the present
invention, at least one of the raceway surface of the bearing ring,
the rolling contact surface of the rolling element and the guide
surface of the pocket of the cage for guiding the rolling element
may be coated with titanium oxide. In this case, the lubricating
property of at least one of the raceway surface of the bearing
ring, the rolling contact surface of the rolling element and the
guide surface of the pocket of the cage for guiding the rolling
element, which are coated with hydrophilic material, can be made
excellent over a long period of time.
[0035] In the ball bearing of the first embodiment described above,
the rolling element is the ball 3. However, in the present
invention, the rolling element may be a cylindrical roller, a
tapered roller or a spherical roller, that is, the rolling element
may be a rolling element except for a ball.
[0036] In the ball bearing of the first embodiment described above,
the shielding plates 6, 7 are arranged on both sides in the axial
direction between the outer ring 1 and the inner ring 2, that is,
one shielding plate is arranged on each side. However, in the
present invention, the seal device is not limited to the shielding
plate but the seal device may be a seal device having a sliding
contact lip formed out of a core bar and an elastic portion. In the
present invention, the seal device is not limited to the outer ring
fixing type described in the present embodiment but the seal device
may be of the inner ring fixing type. The seal member may be
arranged only on one side in the axial direction between the outer
ring and the inner ring. A portion between the inner and the outer
ring may not be airtightly closed by the seal device.
[0037] In this connection, in the case where the seal device is
arranged only on one side in the axial direction between the outer
and the inner ring and in the case where no seal device is provided
between the outer and the inner ring, titanium oxide is employed as
hydrophilic material. Further, in the case of an environment in
which the sunlight or ultraviolet rays intrude into between the
inner and the outer ring, the contamination attached to the
hydrophilic layer can be dissolved into carbon dioxide by the
photocatalystic action of titanium oxide. Accordingly, in this
case, the hydrophilic layer can be washed and maintained in a clean
condition.
[0038] In the ball bearing of the first embodiment, all the surface
of the cage 4 is coated with hydrophilic material. Further, in the
ball bearing of the first embodiment, as shown in FIG. 1, at the
time of using the ball bearing, the cage 4 is located leaving an
interval with respect to the outer ring 1 and the inner ring 2.
Therefore, an end face outward in the radial direction of the cage
4, which is shown by the reference numeral 30 in FIG. 1, that is, a
portion not coming into sliding contact with other members is not
necessarily coated with hydrophilic material. However, when all the
surface of the cage is coated with hydrophilic material, it is
possible to execute coating simply and quickly as compared with a
case in which a portion of the surface of the cage is coated with
hydrophilic material. For example, in the case of a rolling
bearing, in which the cage comes into slide contact with a
circumferential face of the bearing ring, such as a rolling bearing
in which the cage is guided by a raceway shoulder portion of the
outer ring or the inner ring, when all the surface of the cage is
coated with hydrophilic material, it is possible to prevent the
seizure of the cage and the circumferential surface of the inner
ring or the outer ring by which the cage is guided.
[0039] In the present embodiment, the ball bearing of the present
invention is mounted on a drive shaft of a liquid crystal device.
However, the rolling bearing of the present invention can be
mounted on not only the liquid crystal device but also any device
such as a washing device used in an environment in which water,
steam or chemical fluid containing water is scattering outside the
bearing.
[0040] FIG. 2 is a schematic sectional view in the axial direction
of a ball bearing which is the second embodiment of the rolling
bearing of the present invention.
[0041] Like reference numerals are used to indicate like components
in the ball bearings of the first and the second embodiment and the
duplicate explanations are omitted here. In the ball bearing of the
second embodiment, concerning the same operational effects as those
of the ball bearing of the first embodiment and concerning the
variation, the explanations are omitted here. Only the constitution
and the operational effects different from those of the ball
bearing of the first embodiment and the variation will be explained
here.
[0042] This ball bearing of the second embodiment is different from
that of the first embodiment as follows. The raceway groove 111 of
the outer ring 101 and the raceway groove 121 of the inner ring 102
are not coated with hydrophilic material such as titanium oxide but
coated with solid lubricant. The other constitution is the same as
that of the ball bearing of the first embodiment.
[0043] Examples of the above solid lubricant are: graphite,
graphite fluoride, carbon fluoride, hexagonal boron nitride, mica
fluoride, gold, silver, lead, magnesium, tungsten disulfide,
molybdenum disulfide, graphite, tetrafluoride ethylene, Teflon,
PFA, MoS.sub.2, WS.sub.2 and mixtures of them.
[0044] According to the ball bearing of the second embodiment
described above, the raceway grooves 111, 121 of the inner and
outer rings 101, 102 and a portion not having a hydrophilic layer
of the rolling contact surface of the ball 3, that is, the raceway
grooves 111, 121 of the inner and outer rings 101, 102 are coated
with solid lubricant and the raceway grooves 111, 121 of the inner
and outer rings 101, 102 have layers made of solid lubricant.
Therefore, the raceway grooves 111, 121 of the inner and outer
rings 101, 102 and the rolling contact surfaces of the balls 3 can
be excellently lubricated.
[0045] In the ball bearing of the second embodiment described
above, the rolling contact surface of the ball 3 and the ball guide
surface 28 of the pocket of the cage 4 are coated with titanium
oxide having a hydrophilic property. On the other hand, the raceway
grooves 111, 121 of the inner and outer rings 101, 102 and a
portion not having a hydrophilic property of the rolling contact
surface of the ball 3, that is, the raceway grooves 111, 121 of the
inner and outer rings 101, 102 are coated with the solid
lubricant.
[0046] However, in the present invention, at least one of the
raceway grooves of the inner and outer ring, the rolling contact
surface of the ball and the guide surface of the pocket of the cage
may be coated with a hydrophilic material. (A case in which only
the raceway grooves of the inner and outer rings are coated with
hydrophilic material is excluded and a case in which all are coated
with hydrophilic material is also excluded.) At the same time,
members not coated with hydrophilic material in the raceway grooves
of the inner and outer rings and the rolling contact face of the
ball may be coated with solid lubricant.
[0047] In the present invention, at least one of the raceway
grooves of the inner and outer ring, the rolling contact surface of
the ball and the guide surface of the pocket of the cage may be
coated with a hydrophilic material. (A case in which only the
raceway grooves of the inner and outer rings are coated with
hydrophilic material is excluded and a case in which all are coated
with hydrophilic material is also excluded.) At the same time,
members not coated with hydrophilic material in the raceway grooves
of the inner and outer rings, the rolling contact face of the ball
and the ball guide face of the pocket of the cage may be coated
with solid lubricant. Due to the foregoing, all of the raceway
grooves of the inner and outer ring, the rolling contact surface of
the ball and the guide surface of the pocket of the cage can be
preferably lubricated.
[0048] FIG. 3 is a schematic sectional view in the axial direction
of a ball bearing which is the third embodiment of the rolling
bearing of the present invention.
[0049] Like reference numerals are used to indicate like components
in the ball bearings of the first and the third embodiment and the
duplicate explanations are omitted here. In the ball bearing of the
third embodiment, concerning the same operational effects as those
of the ball bearing of the first embodiment and concerning the
variation, the explanations are omitted here. Only the constitution
and the operational effects different from those of the ball
bearing of the first embodiment and the variation will be explained
here.
[0050] The ball bearing of the third embodiment is different from
that of the first embodiment as follows. In ball bearing of the
third embodiment, a surface of the cage 204 is not coated with
hydrophilic material. On the other hand, the ball bearing of the
third embodiment employs a cage 204 made of material to which solid
lubricant is added or alternatively the ball bearing of the third
embodiment employs a cage 204 made of fluororesin having a
lubricating property.
[0051] In this case, examples of the material to which the solid
lubricant is added are: polyamide, polyimide and phenol resin
containing the solid lubricant such as molybdenum disulfide
enumerated in the second embodiment.
[0052] Examples of the fluororesin having a lubricating property
are: tetraethlylene fluoride(polytetrafluoroethylene), teraethylene
fluoride-hexapropylenefluoride copolymer (FEP), tetraethylene
fluoride-perfluoroalkylvinylether copolymer resin (PFA),
tetraethylene fluoride-ethylene copolymer (ETFE), trifluoride
ethylenechloride (PCTFE) and vinylidene fluoride (PVDF).
[0053] According to the ball bearing of the third embodiment, the
cage 204 is made of material, to which solid lubricant is added, or
fluororesin having a property of lubrication. Therefore, when the
ball 3 is rolled at the time of using the ball bearing, the solid
lubricant or the fluororesin is transferred onto the rolling
contact surface of the ball 3 or the raceway surfaces of the inner
and outer rings 1, 2. Therefore, a lubricant film is formed in a
portion to which the solid lubricant or the fluororesin has been
transferred. By the synergistic effect generated by the lubricating
actions of the hydrophilic layer and the cage, the lubrication
property can be remarkably enhanced beyond estimation as compared
with the rolling bearing, the cage of which is made of the material
to which the solid lubricant is added or made of the fluororesin
having a lubricating property.
[0054] In the third embodiment described above, the hydrophilic
material is not coated on the cage at all. However, in the present
invention, a portion of the surface of the cage (for example, only
the rolling element guide surface of the cage) may be coated with
hydrophilic material such as titanium oxide.
[0055] In this connection, of course, the present invention
includes a rolling bearing in which the material of the cage is
changed from PEEK resin (polyether etherketon) or PPS resin
(polyphenylene sulfide) to the material to which the solid
lubricant is added or to the fluororesin having a lubricating
property in the rolling bearing of the first embodiment, the
rolling bearing of the variation of the first embodiment, the
second embodiment or the rolling bearing the variation of the
second embodiment.
* * * * *